WO2005039237A1

WO2005039237A1 - Measurement of hearing aids

Info

Publication number: WO2005039237A1
Application number: PCT/SE2004/001432
Authority: WO
Inventors: Tobias ÖHMAN; Peter Nordqvist
Original assignee: Audeq Hb
Priority date: 2003-10-20
Filing date: 2004-10-07
Publication date: 2005-04-28
Also published as: SE0302766D0

Abstract

The present invention relates to testing and fitting of hearing aid equipment, wherein an interface unit (100) interconnects a computer with a microphone suspension device, such that acoustic signals registered in physical proximity to the hearing aid apparatus can be analyzed in the computer. The interface unit (100) has a computer interface (140) towards the computer and an audio interface (150) towards the microphone suspension device. A galvanic isolation transceiver module (110) receives and transmits electrical signals over the interfaces (140, 150) such that each received signal corresponds to a transmitted signal while a galvanic isolation is maintained between any received and transmitted signals. A computer side (C) of the interface unit (100) is supplied with electrical power (Pin) from a bi-directional serial link (145) connected to the computer interface (140).

Description

jw/

Ref.: 55895 SE

Applicant: Audeq HB

Measurement of Hearing Aids

THE BACKGROUND OF THE INVENTION AND PRIOR ART

The present invention relates generally to testing and fitting of hearing aid equipment. More particularly the invention relates to an interface unit according to the preamble of claim 1 and a system for conducting performance measurements with respect to a hearing aid apparatus when the apparatus is mounted on a patient according to the preamble of claim 14.

When fitting hearing aid equipment to patients it is vital that the characteristics of the equipment are set so that the patient's hearing-impairment is compensated for as well as possible. Ade- quate and accurate acoustic measurements are crucial in order to accomplish this. Typically, such measurements require that one or more microphones be mounted very close to the hearing aid equipment, and preferably that sound is received between the amplifying speaker and the eardrum. For example, the U.S. patent No. 6, 154,546 describes a probe microphone for performing sound measurements within a patient's ear, and thus enables an adequate fitting of a hearing aid. A related solution is described in the published International Patent Application WO02/50499 according to which it is made possible to in-situ determine the acoustic seal provided by an in-ear device, such as a hearing aid.

In order to analyze the registered sounds, the signals from microphones need to be fed to a computer, or equivalent processing tool. Thus, a communication link is required between at least one patient-near microphone and the computer. However, this type of link cannot be established without certain safety precautions. Namely, since the computer contains electrical energy sources, which are potentially hazardous, these energy sources should be isolated from the patient.

The company Siemens AG offers audiometric equipment in the form of a PC-based integrated testing and fitting system called Unity™. This system enables measurements on an ear mounted hearing aid by means of a probe microphone. Here, the PC receives a signal from the probe microphone via a so-called security box, which safeguards the patient against any over- voltages from the PC. A company called Aurical manufactures another PC-based system through which it possible to evaluate how well a hearing aid instrument meets the needs of a parti- cular patient. Also in this case, the PC receives a signal from a probe microphone via an interfacing unit.

Nevertheless, the power supply to the above-mentioned interfacing units is problematic. Either a separate power supply must be arranged to the interfacing unit, or the computer must be pro- vided with specific circuitry for interfacing safely with the probe microphones. In both cases, the design becomes inflexible and relative expensive.

SUMMARY OF THE INVENTION

The object of the present invention is therefore to provide an improved solution, which alleviates the above problems, and thus offers testing and fitting of hearing aid equipment, which is comparatively cost efficient and flexible.

According to one aspect of the invention the object is achieved by the interfacing unit as initially described, wherein the computer interface is adapted to communicate over a bi-directional serial link, which has a capability to transmit electrical power. Moreover, the computer interface is adapted to supply all circuitry on the computer side with electrical power received via the bi-directional serial link.

An important advantage attained by this interfacing unit is that on one hand, it enables microphone signals to be transmitted to the computer, and on the other hand, it prevents any potentially hazardous electrical energy sources inside the computer from contacting electrically with the patient. At the same time, the computer side is provided with electrical power.

According to a preferred embodiment of this aspect of the inven- tion, the interface unit comprises a battery unit, which is adapted to supply outgoing electrical power to at least one microphone via the audio interface. Preferably, the battery unit is also adapted to supply at least one circuit on the patient side with electrical power. Of course, this is advantageous because there- by a power supply of the interface unit is accomplished, which is safe for the patient.

According to another preferred embodiment of this aspect of the invention, the interface unit comprises a transformer unit, which interfaces both the computer side and the patient side of the interfacing unit. The transformer unit is adapted to receive incoming electrical power via the computer interface and supply outgoing electrical power to at least one microphone via the audio interface. Preferably, the transformer unit is also adapted to supply at least one circuit on the patient side with electrical power. Thereby, not only the patient safety requirements are fulfilled, however also the power supply of the interface unit is accomplished efficiently.

According to yet another preferred embodiment of this aspect of the invention, the interface unit comprises a serial link circuit, which is adapted to convert signals between a serial signal format used on the bi-directional serial link and a parallel signal format used inside the interface unit. Thus, a straightforward access to the signals received via the serial link is accom- pushed, and any signals originating in, or passing through the interfacing unit from the at least one microphone, may be converted to the signal format of the serial link.

According to still another preferred embodiment of this aspect of the invention, the interface unit comprises a pre-amplifier circuit, which is adapted to receive the at least one microphone signal, and in response thereto produce at least one amplified microphone signal. Hence, the quality of the registered sounds may be enhanced, which naturally, is desirable.

According to another preferred embodiment of this aspect of the invention, the interface unit comprises a filter circuit, which is adapted to receive at least one of the at least one amplified microphone signal and in response thereto produce at least one filtered microphone signal. Such filtering is advantageous be- cause thereby the dynamics of the microphone signals may be adjusted to fit the dynamic range of any subsequent processing in the interfacing unit, for instance by means of an A/D-con- verter.

According to yet another preferred embodiment of this aspect of the invention, the computer interface is adapted to receive at least one first signal from the external computer. The at least one first signal specifies at least one filter coefficient of the filter circuit. Thus, the filter characteristics may be altered from the computer. Naturally, this is a convenient way to optimize the processing of the microphone signals.

According to another preferred embodiment of this aspect of the invention, the serial link circuit is adapted to detect at least one property of the at least one microphone, and transmit at least one microphone status signal over the computer interface. The at least one microphone status signal reflects the at least one property. Preferably, the property pertains to a number of microphones being connected to the audio interface, or whether the at least one microphone signal represents an audio signal in stereo or in mono. This status detection is desirable, since thereby important information regarding the microphone capability can be supplied to the computer in a very efficient manner.

According to a preferred embodiment of this aspect of the inven- tion, the serial link circuit is adapted to receive an identity request over the computer interface, and in response thereto transmit an identity message over the computer interface. The identity message specifies unique data, which represents the interface unit. Again, this is a feature, which provides the computer is with valuable information when performing a performance measurement.

According to another aspect of the invention the object is achieved the system as initially described, wherein the intermediary unit is represented by the proposed interface unit. The advantages of the system according to the invention are apparent from the discussion hereinabove with reference to the interface unit.

According to a preferred embodiment of this aspect of the invention, the microphone suspension device includes a first micro- phone and a second microphone. The first microphone is provided with means adapted to receive sounds between the hearing aid apparatus and the patient's eardrum. The second microphone is adapted to receive an ambient sound outside the hearing aid apparatus. The second microphone has a reception main lobe axis. The second microphone is arranged in the microphone suspension device, so that the reception main lobe axis is directed substantially perpendicular to an ear-to-ear axis of the patient when the microphone suspension device is mounted on the patient. Such an arrangement of the second micro- phone is desirable because thereby one and the same microphone suspension device may be used for testing hearing aid apparatuses both at the left and the right ear, without the reception main lobe is required be rotation symmetric. According to another preferred embodiment of this aspect of the invention, the second microphone is arranged in the microphone suspension device, such that the reception main lobe axis is directed forwards and substantially horizontal when the micro- phone suspension device is mounted on a patient having an upright position. Namely, this further reduces the requirements with respect to the characteristics of the reception main lobe and is therefore desirable.

Consequently, in the light of the above, the invention offers an excellent means for conducting efficient and reliable performance measurements with respect to a wide variety of hearing aid apparatuses.

Further advantages, advantageous features and applications of the present invention will be apparent from the following des- cription and the dependent claims.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention is now to be explained more closely by means of preferred embodiments, which are disclosed as examples, and with reference to the attached drawings. Figure 1 illustrates a general system according to the invention,

Figure 2 shows a block diagram over an interface unit according to one preferred embodiment of the invention, and Figure 3 shows a block diagram over an interface unit according to another preferred embodiment of the invention.

DESCRIPTION OF PREFERRED EMBODIMENTS OF THE INVENTION Figure 1 illustrates a general system according to the invention. An interface unit 100 here interconnects a computer 200 with a microphone suspension device 300. It is presumed that the microphone suspension device 300 is located in physical proximity to a hearing aid apparatus (not shown), which in turn, is pre- sumed to be mounted on a patient.

The computer 200 is adapted to analyze acoustic signals, for example by means of appropriate software. The microphone suspension device 300 includes one or more microphones 310, 320, which are adapted to receive acoustic signals in physical proximity to the hearing aid apparatus. In response to any received acoustic signal, each of the microphones 310, 320 produces a corresponding microphone signal of an electrical signal format.

For example, a first microphone 310 in the device 300 may be provided with a means 315 (such as a probe), which is adapted to receive sounds between the hearing aid apparatus and the patient's eardrum. A second microphone 320 may be adapted to receive an ambient sound outside the hearing aid apparatus, such that it is possible to evaluate the amplification and filtration accomplished by the hearing aid apparatus by comparing the signals registered by the first and second microphones 310 and 320 respectively. Each microphone 310, 320 is located in a particular compartment in the device 300, and these compartments are acoustically well isolated from one other.

Preferably, the second microphone 320 is arranged in the device 300, such that its reception main lobe axis is directed substantially perpendicular to an ear-to-ear axis of the patient when the device 300 is mounted on the patient. Moreover, it is preferable if the second microphone 320 is arranged, such that the re- ception main lobe axis is directed forwards and substantially horizontal when the microphone suspension device 300 is mounted on a patient having an upright position. This namely relaxes the requirements for the reception main lobe, so that one and the same microphone suspension device may be used for testing hearing aid apparatuses both at the left and the right ear, without the lobe having to be rotation symmetric.

The interface unit 100 is physically separated from the computer 200, and connected thereto via a bi-directional serial link 145, for instance operating according to a USB protocol (USB = Universal Serial Bus). The interface unit 100 is also (preferably physically separated from and) connected to the microphone suspension device 300 via an audio cable 155. Thus, the audio cable 155 and the bi-directional serial link 145 interconnect the computer 200 with the microphone suspension device 300 over the interface unit 100.

Thereby, microphone signals may be transmitted from the microphones 310 and 320 to the computer 200. According to the invention, certain settings of the interface unit 100 may be altered from the computer 200 by means of the bi-directional serial link 145, and in addition to microphone signals, status information (for instance related to the capabilities of the microphones 310 and 320) may be transmitted from the interface unit 100 to the computer. Moreover, the interface unit 100 accomplishes a galvanic isolation between the computer 200 and the microphone suspension device 300, such that any potentially hazardous electrical energy sources inside the computer 200 are prevented from contacting electrically with the patient.

Figure 2 shows a block diagram over the above interface unit 100 according to one preferred embodiment of the invention. The interface unit 100 includes a computer interface 140, an audio interface 150 and a galvanic isolation transceiver module 1 10.

The computer interface 140 is adapted to exchange electrical signals s_{1 t} s₂ s_k, ... , s_n with an external computer 200.

Additionally, the computer interface 140 is capable of transmitting electrical power P_in from the computer 200 to the interface unit 100. The audio interface 150 is adapted to receive micro- phone signals ITH and m₂, which have an electrical signal format. Thus, the interface unit 100 may receive output data from the microphones 310 and 320 via the audio interface 150.

The galvanic isolation transceiver module 1 10 is adapted to receive and transmit electrical signals, such that each received signal corresponds to a transmitted signal while a galvanic isolation is maintained between any received and transmitted signals. Specifically, the galvanic isolation transceiver module 1 10 is arranged, such that it electrically separates a computer side C from a patient side P in the unit 100, where the computer side C is electrically connected to the computer interface 140, and correspondingly, the patient side P is electrically connected to the audio interface 150. The galvanic isolation transceiver module 1 10 may accomplish the electrical separation between the receiver and the transmitter side by converting the signals into an intermediate optical or a magnetic format. However, other intermediate formats are also conceivable according to the invention.

Preferably, according to this embodiment of the invention, the interface unit 100 also includes a battery unit 120a, which is adapted to supply outgoing electrical power P_out to at least one microphone, for example 310 and 320 of the figure 1. This power supply is accomplished via the audio interface 150. The battery unit 120a may also be adapted to supply at least one circuit on the patient side P of the interface unit 100 with electrical power P_P. The figure 2 illustrates this by means of power supply lines to each of a plurality of circuits 160, 165, 170 and 175 respectively. The electrical power P_P fed to the different circuits may, however, vary in terms of voltage and/or current level depending on the specific requirements of the circuit.

Additionally, the interface unit 100 may include a serial link circuit 130, which is adapted to convert signals between a serial signal format used on the bi-directional serial link 145 and a parallel signal format used inside the interface unit 100. Consequently, the serial link circuit 130 renders any signals transmitted from the computer 200 to the interface unit 100 readily accessible on the computer side C of the unit 100.

For example, the galvanic isolation transceiver module 110 may receive at least one signal Si and s₂ specifying one or more filter coefficients, which originate from the computer 200 and have reached the interface unit 100 via the bi-directional serial link 145. Based on the signals s-i and s₂, the galvanic isolation transceiver module 1 10 delivers corresponding filter coefficient sig- nals s-_t' and s₂' on the patient side P. The filter coefficients indicated by s-i' and s₂' designate parameters of a filter circuit 165, which will be further described below.

As mentioned above, the computer interface 140 is adapted to receive microphone signals mi and m₂ of an electrical signal format. The signals m-i and m₂ are preferably fed to a preamplifier circuit 160, which in response to the received signals m-i and m₂ produces corresponding amplified microphone signals m_pι and m_p2 respectively. The filter circuit 165 may then receive the amplified microphone signals m_pι and m_p2, and in response thereto produce filtered microphone signals m^ and m'₂. Hence, the signals s-i' and s₂' influence the filtering characteristics of the filter circuit 165. Preferably, the signals s-i' and s₂' are controlled to designate such coefficients that the dynamics of the filtered microphone signals m^ and m'₂ becomes optimized with respect to a subsequent processing of the signals, for instance in an A/D-converter 175.

However, before reaching the A/D-converter 175, the filtered microphone signals m^ and m'₂ may be subjected to additional amplification in a secondary amplifier 170. The secondary amplifier 170 linearly increases the amplitude of the filtered microphone signals m'^ and m'₂ by delivering corresponding secondary amplified microphone signals M'ι and M'₂. The A/D- converter 175, in turn, receives the secondary amplified microphone signals M'ι and M'₂, and in response thereto produces corresponding digital signals Di and D₂. The galvanic isolation transceiver module 1 10 receives the digital signals D_{1 f} D₂ and processes them before they are transmitted over the bi-directional serial link 145 via the serial link circuit 130 and the computer interface 140.

Naturally, one or more of the circuits 160 - 175 in the processing chain for the microphone signals ITH and m₂ may be omitted according to the invention. Thus, theoretically, the microphone signals m-i and m₂ could be fed directly into the galvanic iso- lation transceiver module 1 10, instead of passing through the pre-amplifier 160, the filtering circuit 165, the secondary amplifier 170 and/or the A/D-converter 175.

According to a preferred embodiment of the invention, the serial link circuit 130 is adapted to detect at least one property of any microphone connected to the audio interface 150, and to transmit at least one microphone status signal, say s_k, reflecting the detected property, over the computer interface 140. This property may pertain to a number of microphones being connected to the audio interface, and/or whether the microphone signals m^ m₂ represent audio signals in stereo or in mono. Namely, when analyzing the audio signals in the computer 200, it is important to know if, for example, two incoming signals represent two stereo channels from one stereo microphone, or two mono signals from two different microphones. Therefore, the microphone status signal s_k renders the computer's 200 processing more efficient.

Moreover, the serial link circuit 130 may be adapted to receive an identity request from the computer 200 over the computer interface 140. In response to this request, the serial link circuit 130 returns an identity message over the computer interface 140. The identity message specifies unique data representing the interface unit 100, such that based on this message, the computer 200 may determine which interface unit 100 is connected to the computer. Furthermore, the interface unit 100 may include a drive circuit 180 adapted to deliver a signal to a loudspeaker 190. The drive circuit 180, in turn, receives its input signal s_n from the computer interface 140 via the serial link circuit 130. The loudspeaker 190 may thus produce a reference sound during the measurements. Alternatively, a pair of earphones may be connected to the drive circuit 180.

Figure 3 shows a block diagram over an interface unit according to another preferred embodiment of the invention. Reference numerals identical to those of figure 2, here denote the same elements as described above with reference to the figure 2.

In this case, however, instead of the battery unit 120a, the interface unit 100 includes a transformer unit 120b. The transformer unit 120b interfaces both the computer side C and the patient side P of the interface unit 100. The transformer unit 120b is adapted to receive incoming electrical power P_in via the computer interface 140, and supply outgoing electrical power P_out to at least one microphone 310, 320 via the audio interface 150.

Preferably, the transformer unit 120b is also adapted to supply one or more circuits on the patient side P with electrical power Pp. For reasons of simplicity, the figure 3 only shows a common power supply line to all the circuits 160, 165, 170 and 175. However, according to the invention, a separate power supply line may be provided to each circuit, so that the electrical power Pp fed to each circuit meets the specific requirements of the circuit in terms of voltage and/or current level.

The term "comprises/comprising" when used in this specification is taken to specify the presence of stated features, integers, steps or components. However, the term does not preclude the presence or addition of one or more additional features, integers, steps or components or groups thereof.

The invention is not restricted to the described embodiments in the figures, but may be varied freely within the scope of the claims.

Claims

1. An interface unit (100) adapted to enable computer based performance measurements with respect to a hearing aid apparatus when said hearing aid apparatus is mounted on a patient, the interface unit ( 100) comprising: a computer interface (140) adapted to exchange electrical signals (s-i , s₂, ... , s_n) with an external computer (200), an audio interface ( 150) adapted to receive at least one microphone signal (m_{1 f} m₂) having an electrical signal format, a galvanic isolation transceiver module (1 10) adapted to receive and transmit electrical signals such that each received signal corresponds to a transmitted signal while a galvanic isolation is maintained between any received and transmitted signals, the module (1 10) being arranged such that it electrically separates a computer side (C) from a patient side (P) in the unit ( 100), the computer side (C) being electrically connected to the computer interface (140) and the patient side (P) being electrically connected to the audio interface (150), characterized in that the computer interface ( 140) is adapted to communicate over a bi-directional serial link (145) having a capability to transmit electrical power, and the computer interface (140) is adapted to supply all circuitry (1 10, 130, 180) on the computer side (C) with electrical power (P_in) received via the bi-directional serial link (145).

2. An interface unit ( 100) according to claim 1 , characterized in that it comprises a battery unit (120a) adapted to supply outgoing electrical power (P_out) to at least one microphone (310, 320) via the audio interface (150).

3. An interface unit (100) according to claim 2, characterized in that the battery unit (120a) is adapted to supply at least one circuit ( 160, 165, 170, 175) on the patient side (P) with electrical power (Pp).

4. An interface unit (100) according to claim 1 , characterized in that it comprises a transformer unit (120b) interfacing both the computer side (C) and the patient side (P), the transformer unit (120b) being adapted to receive incoming electrical power (P_m) via the computer interface (140) and supply outgoing electrical power (P_out) to at least one microphone (310, 320) via the audio interface (150).

5. An interface unit (100) according to claim 4, characterized in that the transformer unit (120b) is adapted to supply at least one circuit (160, 165, 170, 175) on the patient side (P) with electrical power (P_P).

6. An interface unit ( 100) according to any one of the preceding claims, characterized in that it comprises a serial link circuit (130) adapted to convert signals between a serial signal format used on the bi-directional serial link (145) and a parallel signal format used inside the interface unit (100).

7. An interface unit (100) according to any one of the preceding claims, characterized in that it comprises a pre-amplifier circuit (160) adapted to receive the at least one microphone signal (mi, m₂) and in response thereto produce at least one amplified microphone signal (m_pι , m_p2).

8. An interface unit ( 100) according to claim 7, characterized in that it comprises a filter circuit (165) adapted to receive at least one of the at least one amplified microphone signal (m_p , m_p2) and in response thereto produce at least one filtered microphone signal (m'_{1 (} m'₂).

9. An interface unit ( 100) according to claim 8, characterized in that the computer interface (140) is adapted to receive at least one first signal (si , s₂) from the external computer (200), the at least one first signal (si , s₂) specifying at least one filter coefficient of the filter circuit (165).

10. An interface unit (100) according to any one of the claims 6 to 9, characterized in that the serial link circuit (130) is adapted to detect at least one property of the at least one microphone (310, 320), and transmit at least one microphone status signal over the computer interface (140), the at least one microphone status signal reflecting said at least one property.

11. An interface unit (100) according to claim 10, characterized in that at least one of the at least one property pertains to a number of microphones (310, 320) being connected to the audio interface (150).

12. An interface unit (100) according to any one of the claims 10 or 11 , characterized in that at least one of the at least one property relates to whether the at least one microphone signal (rriι , m₂) represents an audio signal in stereo or in mono.

13. An interface unit (100) according to any one of the claims 6 to 12, characterized in that the serial link circuit (130) is adapted to receive an identity request over the computer interface (140), and in response thereto transmit an identity message over the computer interface (140), the identity message speci- fying unique data representing the interface unit (100).

14. A system for conducting performance measurements with respect to a hearing aid apparatus when said hearing aid apparatus is mounted on a patient, comprising: a computer (200) adapted to analyze acoustic signals, a microphone suspension device (300) including at least one microphone (310, 320) adapted to receive acoustic signals in physical proximity to said hearing aid apparatus and in response thereto produce at least one corresponding microphone signal (m_{1 t} m₂), and an intermediary unit (100), physically separated from the computer (200), and adapted to interconnect the computer (200) with the microphone suspension device (300) such that at least one microphone signal (m-i , m₂) may be transmitted from the at least one microphone (310, 320) to the computer (200), and at the same time, any potentially hazardous electrical energy sources inside the computer (200) are electrically isolated from the microphone suspension device (300), characterized in that the intermediary unit (100) is represented by the interface unit according to any one of the claims 1 to 13.

15. A system according to claim 14, characterized in that the microphone suspension device (300) comprises: a first microphone (310) which is provided with means

(315) adapted to receive sounds between the hearing aid apparatus and the patient's ear drum, and a second microphone (320) adapted to receive an ambient sound outside the hearing aid apparatus, the second micro- phone (320) having a reception main lobe axis, and the second microphone (320) being arranged in the microphone suspension device (300) such that the reception main lobe axis is directed substantially perpendicular to an ear-to-ear axis of the patient when the microphone suspension device (300) is mounted on the patient.

16. A system according to claim 15, characterized in that the second microphone (320) is arranged in the microphone suspension device (300) such that the reception main lobe axis is directed forwards and substantially horizontal when the microphone suspension device (300) is mounted on a patient having an upright position.